Textbook: Chapter 2.2 Page 62 Question #27

27. The mean of six rational numbers is -4.3.

     a) What is the sum of the rational numbers?   

      b) If five of the numbers each equal -4.5, what is the sixth number?  

a)  -4.3 x 6 = -25.8 

b) You multiply -4.5 by 5 to get the sum of the first 5 numbers.

 -4.5 x 5 = -22.5a

Then you subtract -22.5 from -25.8 

-25.8 - (-22.5) = -3.3 

So, the sixth number is -3.3

Link

Link 2